KR101748011B1 - Adhesive composition for polarizing plate, adhesive film for polarizing plate prepared using the same, polarizing plate comprising the same and optical display comprising the same - Google Patents

Abstract

(Meth) acryl-based copolymer, an isocyanate-based crosslinking agent, and a silane coupling agent, wherein the molar ratio (A) of the hydroxyl group of the (meth) acrylic copolymer is from 2.5 mol% to 4 mol% (B) of the alkoxysilane group of the silane coupling agent in the total sum of the number of moles of the alkoxysilane group of the coupling agent and the number of moles of the isocyanate group of the isocyanate crosslinking agent is 50 mol% to 80 mol%, the isocyanate group (C) is from 20 mol% to 50 mol%, a pressure-sensitive adhesive film for a polarizing plate formed from the composition, a polarizing plate comprising the same, and an optical display device comprising the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure-sensitive adhesive composition for a polarizing plate, an adhesive film for a polarizing plate formed therefrom, a polarizing plate including the same, and an optical display device including the polarizing plate. THE SAME}

The present invention relates to a pressure-sensitive adhesive composition for a polarizing plate, a pressure-sensitive adhesive film for a polarizing plate formed from the same, a polarizing plate comprising the same, and an optical display device comprising the same.

A liquid crystal display device includes a polarizing plate laminated on both surfaces of a liquid crystal display panel. The polarizer includes a polarizer and a protective film formed on both sides of the polarizer. The polarizing plate may be laminated on the liquid crystal display panel by forming an adhesive layer on one side of the protective film. A polarizing plate having a protective film formed on only one side of the polarizer (when the protective film is a triacetyl cellulose (TAC) film, it is referred to as a TACless polarizing plate) has a material cost reduction and a polarizing plate thinning effect.

The TACless polarizing plate has a protective film formed only on one side of the polarizer, so that the bending value is high and the durability and reliability of the polarizing plate may not be good. (Meth) acryl-based copolymer polymerized with a monomer mixture containing a carboxylic acid group-containing monomer in the adhesive layer in order to improve durability and reliability. However, such a pressure-sensitive adhesive layer may be corroded by a carboxylic acid group when used in a plane-to-line switching (PLS) or an in-plane switching (IPS) liquid crystal panel coated with ITO (indium tin oxide) metal.

In addition, since the TACless polarizer directly contacts the polarizer and the adhesive layer, adhesion between the polarizer and the adhesive layer must be good for reworkability. However, the conventional adhesive layer alone has a limitation in increasing the adhesion between the polarizer and the adhesive layer. Also, since the polarizer and the adhesive layer are in direct contact with each other in the TACless polarizer, cracks of the polarizer are likely to occur under high temperature and / or high humidity conditions. To solve this problem, the adhesive layer should have good adhesion to the polarizer. Conventionally, only the adhesive layer has a limitation in heightening the adhesion. In this connection, Japanese Laid-Open Patent Application No. 0-067275 discloses an adhesive for a polarizing plate and a polarizing plate with a pressure-sensitive adhesive using the same.

An object of the present invention is to provide a pressure-sensitive adhesive composition for a polarizing plate, which is used for a polarizing plate comprising a polarizer and a protective film formed only on one surface of a polarizer, and which is capable of realizing an adhesive film having good humidity resistance, heat resistance reliability and low bending value.

Another object of the present invention is to provide a pressure-sensitive adhesive composition for a polarizing plate capable of realizing a pressure-sensitive adhesive film which is free from corrosion on a metal coating or the like when used in a liquid crystal display panel.

It is still another object of the present invention to provide a pressure-sensitive adhesive composition for a polarizing plate capable of realizing a pressure-sensitive adhesive film having high adhesion to a polarizer.

The pressure sensitive adhesive composition for a polarizing plate of the present invention comprises a (meth) acrylic copolymer, an isocyanate crosslinking agent and a silane coupling agent, wherein the molar ratio (A) of the hydroxyl group of the (meth) acrylic copolymer is 2.5 mol% to 4 mol% (B) of the alkoxysilane group of the silane coupling agent to the total sum of the number of moles of the alkoxysilane group of the silane coupling agent and the number of moles of the isocyanate group of the isocyanate crosslinking agent is from 50 mol% to 80 mol %, And the ratio (C) of the number of moles of isocyanate groups in the isocyanate-based crosslinking agent is from 20 mol% to 50 mol%.

The adhesion of the polarizing plate for a polarizing plate of the present invention may be 1,000 gf / inch or more.

The polarizing plate of the present invention may include the above-mentioned pressure sensitive adhesive film for a polarizing plate.

The optical display device of the present invention may include the polarizing plate.

The present invention provides a pressure-sensitive adhesive composition for a polarizing plate, which is used in a polarizing plate including a polarizer and a protective film formed only on one side of a polarizer, and which can realize an adhesive film having good humidity resistance, heat resistance reliability and low bending value. The present invention provides a pressure-sensitive adhesive composition for a polarizing plate capable of realizing a pressure-sensitive adhesive film having no corrosion on a metal coating or the like when used in a liquid crystal display panel. The present invention provides a pressure-sensitive adhesive composition for a polarizing plate capable of realizing a pressure-sensitive adhesive film having high adhesion to a polarizer.

1 is a sectional view of a polarizing plate of an embodiment of the present invention.
2 is a cross-sectional view of a liquid crystal display device according to an embodiment of the present invention.

The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

As used herein, "(meth) acryl" means acrylic and / or methacrylic, and "(meth) acrylate" means acrylate and / or methacrylate.

In this specification, the terms 'upper' and 'lower' refer to the drawings and are not necessarily fixed to the upper and lower portions, but the upper, lower, upper, . ≪ / RTI >

In the present specification, the "molar ratio (A) of the hydroxyl group of the (meth) acrylic copolymer" is defined as the sum of the number of moles of the monomers contained in the monomer mixture for the (meth) (Unit: mol) of the (meth) acrylic monomer is a2, it can be a2 / a1 x 100.

(The number of moles of the silane coupling agent in the pressure-sensitive adhesive composition) x (the number of alkoxysilane groups contained in one molecule of the silane coupling agent) b is the number of moles of the alkoxysilane group of the silane coupling agent The number of moles of the isocyanate crosslinking agent in the composition x the number of isocyanate groups contained in one molecule of the isocyanate crosslinking agent) is c / (b + c) x 100.

(Number of moles of silane coupling agent in the pressure-sensitive adhesive composition) x (number of alkoxysilane groups contained in one molecule of the silane coupling agent) is referred to as b, and " number of moles of isocyanate group The number of moles of the isocyanate crosslinking agent in the pressure-sensitive adhesive composition x the number of isocyanate groups contained in one molecule of the isocyanate crosslinking agent) is c / (b + c) x 100.

Hereinafter, the pressure-sensitive adhesive composition for a polarizing plate of one embodiment of the present invention will be described.

The pressure-sensitive adhesive composition for a polarizing plate of one embodiment of the present invention can be used for attaching a polarizing plate to a panel of an optical display device including a polarizer and a polarizing plate including an optical film formed on one side of the polarizing film. The pressure sensitive adhesive composition for a polarizing plate according to one embodiment of the present invention comprises a (meth) acrylic copolymer, an isocyanate crosslinking agent and a silane coupling agent, wherein the molar ratio A of the hydroxyl group of the (meth) acrylic copolymer is from 2.5 mol% to 4 mol% , The molar ratio (B) of the alkoxysilane group of the silane coupling agent is 50 mol% to 80 mol%, and the molar ratio (C) of the isocyanate group (NCO) of the isocyanate crosslinking agent is 20 mol% to 50 mol%.

(A) of the hydroxyl group of the (meth) acrylic copolymer may be 2.5 mol% to 4 mol%. In the above range, the hydroxyl group of the (meth) acrylic copolymer reacts with the silane coupling agent and the crosslinking agent to form a hydrogen bond with the hydroxyl group of the polarizer, particularly the polyvinyl alcohol polarizer, and the crosslinking agent connects the hydroxyl group of the adhesive layer to the hydroxyl group of the polarizer The adhesion between the polarizer and the pressure-sensitive adhesive film can be increased, and the durability and reliability of the polarizer can be enhanced.

The molar ratio (B) of the alkoxysilane group of the silane coupling agent may be 50 mol% to 80 mol%, and the molar ratio (C) of the isocyanate group of the isocyanate crosslinking agent may be 20 mol% to 50 mol%. The hydroxyl group contained in the (meth) acrylic copolymer and the polyvinyl alcohol polarizer reacts with the alkoxysilane group of the silane coupling agent and the isocyanate group of the crosslinking agent. Within the above range, the hydroxyl group of the polyvinyl alcohol polarizer and the alkoxysilane group of the silane coupling agent can react with each other, thereby enhancing the adhesion between the polarizer and the adhesive layer, and enhancing durability and reliability.

B > C, the effect of suppressing the warping of the polarizing plate can be large. Specifically, when B > C, the number of moles of the isocyanate group is small and the effect of suppressing the warping of the polarizing plate can be greater. More specifically, the difference (B-C) between B and C can be 5 mol% to 56 mol%, specifically 20 mol% to 56 mol%.

The (meth) acrylic copolymer can be cured by an isocyanate-based crosslinking agent to increase the mechanical strength of the pressure-sensitive adhesive layer. The (meth) acrylic copolymer is preferably a (meth) acrylic monomer having a hydroxyl group; And a monomer mixture containing at least one of (meth) acrylic monomers having an alkyl group, (meth) acrylic monomers having a heterocyclic ring, (meth) acrylic monomers having an aromatic group, and (meth) acrylic monomers having an alicyclic group .

The (meth) acrylic monomer having a hydroxyl group may be a (meth) acrylic acid ester having a terminal or an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms having a hydroxyl group in the structure. For example, the (meth) acrylic monomer having a hydroxyl group may be at least one selected from the group consisting of 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxypropyl (meth) acrylate, diethylene (Meth) acrylate, dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, glycol mono (meth) acrylate, 1,6- (Meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclopentyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate May include the rate, and cyclohexane dimethanol mono (meth) acrylate, one or more of, but is not limited to these. The (meth) acrylic monomers having a hydroxyl group may be included singly or in combination of two or more.

The (meth) acrylic monomer having a hydroxyl group may be contained in an amount of from 2.5 mol% to 4.0 mol% in the monomer mixture. A pressure-sensitive adhesive film having a high adhesion to a polarizer, a high releasability, a high durability, a bending of a polarizing plate and a crack of a polarizer can be realized within the above range.

The (meth) acrylic monomer having an alkyl group can improve the reliability of the adhesive layer. The (meth) acrylic monomer having an alkyl group may include a (meth) acrylic acid ester having a linear or branched unsubstituted alkyl group having 1-20 carbon atoms. For example, the (meth) acrylic monomer having an alkyl group may be selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (Meth) acrylate, octyl (meth) acrylate, iso (butyl) acrylate, iso (butyl) (Meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate and dodecyl (meth) acrylate. The (meth) acrylic monomers having an alkyl group may be used singly or in combination of two or more.

The (meth) acrylic monomer having an alkyl group may be contained in 76 mol% to 97.5 mol% of the monomer mixture. In the above range, a pressure-sensitive adhesive film having higher adhesion to a polarizer, higher re-release property, higher durability, and capable of suppressing warping of a polarizing plate and cracking of a polarizer can be realized. Specifically, it may be contained in an amount of 76 mol% to 97.4 mol% or 96 mol% to 97.5 mol%.

The (meth) acrylic monomer having a heterocyclic ring may be an aliphatic or alicyclic saturated or unsaturated heterocyclic ring having 2 to 10 carbon atoms and having a hetero atom (e.g., at least one of nitrogen, oxygen and sulfur) or an aromatic heterocyclic ring having 4-20 carbon atoms ≪ / RTI > For example, (meth) acryloylmorpholines.

The (meth) acrylic monomer having a heterocyclic ring may be contained at 0.1 mol% to 20 mol% in the monomer mixture. In this range, an adhesive film having high adhesion to a polarizer, high re-peeling property, high durability, and capable of suppressing warping of a polarizing plate and cracking of a polarizer can be realized.

The (meth) acrylic monomer having an aromatic group is an unsubstituted (meth) acrylate having an aromatic group having 6 to 20 carbon atoms, and may be represented, for example, by the following formula (1)

≪ Formula 1 >

(Wherein R ₁ is hydrogen or a methyl group, s is an integer of 0 to 10, R ₂ is a phenoxy group, a phenyl group, a methylphenyl group, a methylethylphenyl group, a methoxyphenyl group, a propylphenyl group, a cyclohexylphenyl group, A phenyl group, a bromophenyl group, a phenylphenyl group, a benzyl group or a benzylphenyl group).

The (meth) acrylic monomer having an aromatic group may be at least one selected from the group consisting of 2-phenoxyethyl (meth) acrylate, phenyl (meth) acrylate, phenoxy (meth) acrylate, (Meth) acrylate, 2-phenylethyl (meth) acrylate, 3-phenylpropyl (meth) acrylate, (Meth) acrylate, 2- (4-methylethyl) phenyl (meth) acrylate, 2- Ethyl (meth) acrylate, 2- (4-methoxyphenyl) ethyl (meth) acrylate, 2- (4-cyclohexylphenyl) ethyl (Meth) acrylate, 2- (4-bromophenyl) ethyl (meth) acrylate, 2- (Meth) acrylate, benzyl (meth) acrylate and 2- (4-benzylphenyl) ethyl (meth) acrylate. no.

The (meth) acrylic monomer having an aromatic group may be contained at 0.1 mol% to 20 mol% in the monomer mixture. In this range, an adhesive film having high adhesion to a polarizer, high re-peeling property, high durability, and capable of suppressing warping of a polarizing plate and cracking of a polarizer can be realized.

The (meth) acrylic monomer having an alicyclic group may include a (meth) acrylic monomer having an alicyclic group having 4 to 20 carbon atoms. For example, the (meth) acrylic monomer having a ring group may include at least one of isobornyl (meth) acrylate and cyclopentyl (meth) acrylate, but is not limited thereto.

The (meth) acrylic monomer having an alicyclic group may be contained at 0.1 mol% to 20 mol% in the monomer mixture. In this range, an adhesive film having high adhesion to a polarizer, high re-peeling property, high durability, and capable of suppressing warping of a polarizing plate and cracking of a polarizer can be realized.

In one embodiment, the monomer mixture for the (meth) acrylic copolymer contains 96.0 mol% to 97.5 mol% of a (meth) acrylic acid ester having an unsubstituted alkyl group having 1 to 20 carbon atoms, an alkyl group having 2 to 20 carbon atoms having a hydroxyl group (Meth) acrylic acid ester having a carboxyl group in the molecule.

In another embodiment, the monomer mixture for the (meth) acrylic copolymer has from 76.0 mol% to 97.4 mol% of a (meth) acrylic acid ester having an unsubstituted alkyl group having from 1 to 20 carbon atoms; 2.5 mol% to 4.0 mol% of a (meth) acrylic acid ester having an alkyl group having 2 to 20 carbon atoms and having a hydroxyl group; And 0.1 mol% to 20.0 mol% of at least one of (meth) acrylic monomers having a heterocyclic ring, (meth) acrylic monomers having an alicyclic group, and (meth) acrylic monomers having an aromatic group.

The (meth) acrylic copolymer may have a weight average molecular weight of from 0 to 2,000,000 g / mol, for example, from 800,000 to 1,000,000 g / mol. Within this range, the reliability is excellent and the light leakage can be suppressed. The weight average molecular weight can be measured by gel permeation chromatography.

(Meth) acrylic copolymer may have a polydispersity index (PDI) of 1.5 to 15, for example, 2 to 7. In the above range, there can be obtained an excellent effect of reliability.

(Meth) acrylic copolymer may have a glass transition temperature of -52 캜 to -27 캜. Within this range, it is possible to provide a good stress relaxation force to the polarizing plate, increase the adhesive force to glass, simultaneously provide high shrinkage resistance, and minimize light leakage.

The (meth) acrylic copolymer may have an acid value of 0.5 mgKOH / g or less, specifically 0.3 mgKOH / g or less. Even if used in PLS and IPS liquid crystal panels in the above range, corrosion of the metal coating of ITO can be prevented.

The method for producing the (meth) acrylic copolymer is not particularly limited, and it can be produced by a solution polymerization method, a photopolymerization method, a bulk polymerization method, an emulsion polymerization method or an emulsion polymerization method. Preferably, the (meth) acrylic copolymer is produced by a solution polymerization method, and the polymerization temperature is preferably from 50 ° C to 140 ° C, and the polymerization time is from 5 hours to 24 hours. As an initiator in the polymerization, an azo-based polymerization initiator such as azobisisobutyronitrile or azobiscyclohexanecarbonitrile; And / or peroxides such as benzoyl peroxide or acetyl peroxide, and the like. The initiator may be included in an amount of 0.01-10 parts by weight based on 100 parts by weight of the (meth) acrylic monomer having an alkyl group. Within this range, the copolymer can be sufficiently polymerized. The solvent for polymerization is not particularly limited, but one or more of ethyl acetate and methyl ethyl ketone may be used.

The isocyanate crosslinking agent cures the (meth) acrylic copolymer, and may include a polyfunctional or higher functional polyisocyanate crosslinking agent, a monofunctional or higher modified polyisocyanate crosslinking agent, or a mixture thereof. In particular, the modified polyisocyanate-based crosslinking agent may have a greater effect of suppressing cracking, releasability and durability of the polarizer.

Specifically, the bifunctional or higher polyisocyanate crosslinking agent includes tolylene diisocyanate (TDI) including hexamethylene diisocyanate (HDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, Xylene diisocyanate (XDI) including methylene diphenyl diisocyanate (MDI), 1,3-xylene diisocyanate and 1,4-xylene diisocyanate, hydrogenated tolylene diisocyanate, isophorone diisocyanate, 1,3- Hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4-trimethylhexamethylene diisocyanate, , Trimethylolpropane-modified toluene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, trimethylol The like trill diisocyanate of ropan air duct, trimethylol propane xylene diisocyanate air duct, triphenylmethane triisocyanate, methylene bis triisocyanate, and is not necessarily limited thereto. These may be used alone or in combination of two or more.

The modified polyisocyanate crosslinking agent may include a crosslinking agent in which the isocyanate group of the bifunctional or higher polyisocyanate crosslinking agent is partially end-capped. For example, the modified polyisocyanate crosslinking agent may be one in which one isocyanate group is end-capped in the bifunctional polyisocyanate-based crosslinking agent, one in which one or two isocyanate groups in the trifunctional polyisocyanate-based crosslinking agent is end-capped, And one to three isocyanate groups in the cross-linking agent may be end-capped. The modified polyisocyanate-based crosslinking agent may be prepared by using a commercially available product, or by end-capping a part of the isocyanate groups by reacting a bifunctional or higher polyisocyanate-based crosslinking agent with an alcohol or the like.

The isocyanate crosslinking agent may be contained in an amount of 0.1 to 10 parts by weight, specifically 0.1 to 5 parts by weight, more specifically 0.1 to 2 parts by weight, based on 100 parts by weight of the (meth) acrylic copolymer. An adhesive film excellent in endurance reliability in the above range and having little change in component and physical properties with time can be realized.

The silane coupling agent is contained in the pressure-sensitive adhesive composition, and it is possible to improve the moisture-proof and moisture-proof heat reliability of the pressure-sensitive adhesive layer. The silane coupling agent may be an alkoxysilane group-containing silane coupling agent known to those skilled in the art. Specifically, the silane coupling agent is an epoxy compound having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) Silicon compounds; (Meth) acrylate group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and (meth) acryloxypropyltrimethoxysilane; Containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane. ; Mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane; And 3-chloropropyltrimethoxysilane, but are not limited thereto. Preferably, the use of the mercapto group-containing silicon compound may further enhance the durability of the pressure-sensitive adhesive film.

The silane coupling agent may be included in an amount of 0.1 to 10 parts by weight, specifically 0.1 to 5 parts by weight, more specifically 0.1 to 1 part by weight, based on 100 parts by weight of the (meth) acrylic copolymer. An adhesive film excellent in endurance reliability in the above range and having little change in component and physical properties with time can be realized.

The pressure-sensitive adhesive composition for a polarizing plate may further contain a solvent for coating properties and coating properties. The solvent is not particularly limited, but methyl ethyl ketone and the like can be used. The pressure-sensitive adhesive composition may further contain conventional additives such as an ultraviolet absorber and an antioxidant.

The pressure-sensitive adhesive composition for a polarizing plate may have a viscosity of 1,000 to 6,000 cP at 25 ° C. Within the above range, the thickness of the adhesive film can be easily adjusted, there is no unevenness in the adhesive film, and the coated surface can have a uniform effect.

Hereinafter, the pressure-sensitive adhesive film for a polarizing plate of one embodiment of the present invention will be described.

The adhesive film for a polarizing plate of the present invention may have an adhesive force of 1,000 gf / inch or more to a polyvinyl alcohol polarizer. It is possible to produce a polarizing plate having a cracking preventing effect, polarizing property and re-peeling property and durability in the above range. Specifically, the adhesion to the polarizer may be 1,000 gf / inch to 1,500 gf / inch. More specifically from 1,000 gf / inch to 1200 gf / inch.

The polyvinyl alcohol polarizer for adhesion measurement may include a polarizer made of a polyvinyl alcohol-based resin. For example, a polyvinyl alcohol film (degree of polymerization: 2,400, degree of saponification: 99%, thickness: 60 탆, VF-PS # 6000 manufactured by Kuraray Co., Ltd.) was expanded in an aqueous solution at 30 캜 and stretched at a stretching ratio of 3.1 times at 30 캜, (Thickness: 22 mu m) prepared by adsorbing iodine in an aqueous 0.02 wt% aqueous solution and stretching it in an aqueous solution of boric acid at 57 DEG C at a draw ratio of 2 to obtain a final draw ratio of 6.2. The pressure-sensitive adhesive film for polarizing plate for adhesion measurement may be a film having a thickness of 5 to 100 탆 obtained by coating the pressure-sensitive adhesive composition for polarizing plate and leaving it at 20 to 35 캜 for 1 hour to 1 week.

The pressure-sensitive adhesive film for a polarizing plate can be produced by drying and / or aging the pressure-sensitive adhesive composition for a polarizing plate of one embodiment of the present invention. Specifically, aging of the pressure-sensitive adhesive composition may include, but is not limited to, thermosetting, or leaving at 20 to 35 占 폚 for 1 hour to 1 week. For example, the pressure-sensitive adhesive film can be produced by coating the pressure-sensitive adhesive composition on a release film (for example, a polyethylene terephthalate film), followed by drying and curing at 20 to 35 ° C.

The thickness of the pressure sensitive adhesive film for a polarizing plate may be 5 占 퐉 to 100 占 퐉, specifically 10 占 퐉 to 50 占 퐉, and within the above range, it may be used as an adhesive film for a polarizing plate.

The pressure-sensitive adhesive film for a polarizing plate may have an acid value of 0.5 mgKOH / g or less, specifically 0.3 mgKOH / g or less. Within the above range, a polarizer excellent in reliability can be provided.

The polarizing plate of the present invention may include an adhesive layer for a polarizing plate of one embodiment of the present invention or an adhesive layer formed of a pressure-sensitive adhesive composition for a polarizing plate of one embodiment of the present invention. Specifically, the polarizing plate includes a polarizer, an optical film formed on one surface of the polarizer, and an adhesive layer formed on the other surface of the polarizer, and the adhesive layer may be formed of the adhesive composition for a polarizing plate of the embodiment of the present invention. The optical film may include at least one of a non-phase difference protective film and a retardation film. Hereinafter, a polarizing plate of one embodiment of the present invention will be described with reference to Fig.

Referring to FIG. 1, a polarizer 100 of an embodiment of the present invention includes a polarizer 110; An optical film 120 formed on the top of the polarizer 110; And a pressure sensitive adhesive layer 130 formed on the lower portion of the polarizer 110. The pressure sensitive adhesive layer 130 may be formed of the pressure sensitive adhesive film or pressure sensitive adhesive composition of one embodiment of the present invention.

The polarizer is made of a polyvinyl alcohol-based film and is not particularly limited as long as it is a polyvinyl alcohol-based film regardless of the manufacturing method. For example, a polarizer may be a modified polyvinyl alcohol film such as a partially-formalized polyvinyl alcohol film or an acetoacetyl-modified polyvinyl alcohol film. Specifically, a polyvinyl alcohol film is prepared by dyeing iodine or a dichroic dye and stretching it in a predetermined direction. Specifically, it is produced through a swelling process, a dyeing process, and a stretching process. Methods of performing each step are commonly known to those skilled in the art. Although the thickness of the polarizer is not particularly limited, it may be, for example, 10 占 퐉 to 50 占 퐉, and it may be used in an optical display device in the above range.

The optical film may be a polyester-based or poly (arylene) -based film including a cyclic olefin polymer including a cyclic olefin polymer (COP), a poly (meth) acrylate-based, a polycarbonate-based, a polyethylene terephthalate Polyamide-based, polyolefin-based, polyacrylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, polyvinylidene chloride-based or mixtures thereof.

Although the thickness of the optical film is not particularly limited, it may be 10 占 퐉 to 200 占 퐉, for example, 30 占 퐉 to 120 占 퐉, and the optical film may be used in an optical display device in the above range.

The adhesive film can be formed by coating the pressure-sensitive adhesive composition of one embodiment of the present invention on one surface of a polarizer, drying and / or curing the adhesive film, and the thickness of the pressure-sensitive adhesive film may be 5 to 100 탆.

The optical display device of the present invention may include a polarizing plate of the embodiment of the present invention, and may be a liquid crystal display device or an organic light emitting diode display device.

Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described with reference to FIG.

2, the liquid crystal display device 200 according to an embodiment of the present invention includes a liquid crystal display panel 210 and a polarizing plate 220 formed on the upper surface of the liquid crystal display panel 210, It can be a polarizing plate of one embodiment of the invention.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Production Example 1: (meth) acrylic copolymer

50 g of ethyl acetate (EAc), 10 g of methyl ethyl ketone (MEK), 100 g of butyl acrylate (n-BA) and 2.5 g of 2-hydroxyethyl methacrylate (2-HEMA) And the temperature was maintained. 0.06 g of azobisisobutyronitrile as an initiator was dissolved in 20 g of ethyl acetate and added. After reacting at 65 DEG C for 3 hours, 170 g of methyl ethyl ketone was added and cooled to 40 DEG C to prepare a methacrylic copolymer having a viscosity of 4,400 cP at 25 DEG C and an acid value of 0 mgKOH / g.

Production Examples 2 to 8: Preparation of (meth) acrylic copolymer

A (meth) acrylic copolymer was produced in the same manner as in Production Example 1, except that the monomer content was changed to the following Table 1 (unit: g).

Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 Production Example 8 Content of monomers (g) n-BA 100 100 100 100 100 100 100 100 2-HEMA 2.5 3.0 4.1 3.4 3.4 3.4 2.0 4.6 IBOA - - - 10 - - - - ACMO - - - - 10 - - - 2-PHEA - - - - - 10 - - The molar ratio (mol%) of the hydroxyl groups of the acrylic copolymer 2.5 3.0 4.0 3.0 3.0 3.0 2.0 4.5

* n-BA: n-butyl acrylate, 2-HEMA: 2-hydroxyethyl methacrylate, IBOA: isobornyl acrylate, ACMO: acryloylmorpholine, 2-PHEA: Late.

Example 1

(BXX-6460, manufactured by Toyo Ink Co., Ltd., molecular weight: 356 g / mol, number of isocyanate groups per one molecule of modified polyisocyanate crosslinking agent) was added to 18 g of methyl ethyl ketone on the basis of the solid content, 100 g of the acrylic copolymer of Production Example 1 and 100 g of the modified polyisocyanate crosslinking agent : 2) and 0.84 g of a silane coupling agent KBM-803 (3-mercaptopropyltrimethoxysilane, manufactured by Shin-Yatsu Co., Ltd., molecular weight: 196 g / mol, number of alkoxy groups per one molecule of silane coupling agent: 3) , And the mixture was stirred at 25 占 폚 for 30 minutes to prepare a pressure-sensitive adhesive composition for a polarizing plate.

Examples 2 to 8

A pressure-sensitive adhesive composition for a polarizing plate was prepared in the same manner as in Example 1, except that the content of the (meth) acrylic copolymer, the crosslinking agent and the silane coupling agent in Example 1 were changed as shown in Table 2 below.

Comparative Examples 1 to 4

A pressure-sensitive adhesive composition for a polarizing plate was prepared in the same manner as in Example 1, except that the content of the (meth) acrylic copolymer, the crosslinking agent and the silane coupling agent in Example 1 were changed as shown in Table 2 below.

(1) to (3) were evaluated for the pressure-sensitive adhesive composition for a polarizing plate of Examples and Comparative Examples, and the pressure-sensitive adhesive film prepared by applying and curing the pressure-sensitive adhesive composition therefrom, and the results are shown in Tables 2 and 3 below.

Example One 2 3 4 5 6 7 Acrylic copolymer type Production Example 1 Production Example 2 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 The acrylic copolymer (g) 100 100 100 100 100 100 100 The molar ratio (mol%) of the hydroxyl groups of the acrylic copolymer 2.5 3.0 3.0 4.0 3.0 3.0 3.0 Silane coupling agent (g) 0.84 0.84 0.36 0.84 0.84 0.84 0.84 Number of moles of silane coupling agent (mol) 0.0043 0.0043 0.0018 0.0043 0.0043 0.0043 0.0043 Isocyanate-based intercourse (g) 0.65 0.65 0.65 0.65 0.65 0.65 0.65 The number of moles (mol) of isocyanate- 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 0.0018 (Mol%) of the alkoxysilane group of the silane coupling agent (mol%) 78 78 60 78 78 78 78 (C) (mol%) of the isocyanate group in the isocyanate-based isocyanate group 22 22 40 22 22 22 22 Heat Resistance Reliability ○ ○ ○ ○ ○ ○ ○ Intrinsic reliability ○ ○ ○ ○ ○ ○ ○ Bending (mm) 1.1 2.7 3.0 3.2 2.5 2.8 3.0 Adhesion to polarizer (gf / ich) 1100 1100 1000 1050 1200 1100 1100

Comparative Example One 2 3 4 Acrylic copolymer type Production Example 7 Production Example 2 Production Example 3 Production Example 8 The acrylic copolymer (g) 100 100 100 100 The molar ratio (mol%) of the hydroxyl groups of the acrylic copolymer 2.0 3.0 4.0 4.5 Silane coupling agent (g) 0.84 1.43 0.15 0.84 Number of moles of silane coupling agent (mol) 0.0043 0.0073 0.0008 0.0043 The isocyanate-based crosslinking agent (g) 0.65 0.65 0.65 0.65 Moles (mol) of isocyanate-based crosslinking agent 0.0018 0.0018 0.0018 0.0018 (Mol%) of the alkoxysilane group of the silane coupling agent (mol%) 78 86 40 78 (C) (mol%) of the isocyanate group of the isocyanate-based crosslinking agent 22 14 60 22 Heat Resistance Reliability △ × × × Intrinsic reliability × △ × × Bending (mm) 1.2 1.5 4.3 4.5 Adhesion to polarizer (gf / inch) 700 900 400 400

As shown in Table 2, the polarizer of the present invention has high heat resistance and moisture resistance reliability and low bending value. Further, the adhesion to the polarizer is high, and the reworkability can be good.

On the other hand, Comparative Examples 1 to 4, in which the ratio of the number of moles of hydroxyl groups to the total number of functional groups in the acrylic copolymer, and the values of (B) and (C) were out of the range of the present invention, were poor in heat resistance and humidity resistance reliability or high in warpage.

(1) Heat Resistance Reliability and Humidity Resistance Reliability: The pressure-sensitive adhesive was applied on a release film, dried to a thickness of 20 μm, and then joined to a polarizer to prepare a polarizing plate. A polarizing plate was laminated on a glass substrate with a size of 100 mm x 175 mm (width x length), and a pressure of 4 to 5 kg was applied to the specimen. In order to investigate the wet heat characteristics of the specimens, 500 hours were left under the condition of 60 ° C / 90% relative humidity, and bubbles or peeling were observed. Heat resistance was measured after standing at 85 ℃ for 500 hours. Both conditions were left at room temperature for more than 1 hour and then observed either through the eyes or through a microscope.

○: No bubbles or peeling.

△: There are some bubbles or peeling phenomenon.

X: Bubbles or peeling occurred.

(2) Flexure: A polyvinyl alcohol film (degree of polymerization: 2,400, degree of saponification: 99%, thickness: 60 탆, VF-PS # 6000 manufactured by Kuraray Co., Japan) was expanded in an aqueous solution at 30 캜, , Iodine was adsorbed in an aqueous 0.02 wt% solution, stretched in an aqueous solution of boric acid at 57 캜 at a stretching ratio of 2, and stretched to give a final stretching ratio of 6.2 to prepare a polarizer (thickness: 22 탆). The prepared polarizer was laminated on a polariser specimen cut into a width x length (205 mm x 20 mm) with a size of 210 mm x 25 mm x 0.5 cm (width x length x thickness). The adhesive film was laminated to 0.5T glass cut into a size of 210 mm x 25 mm x 0.5 cm (width x length x thickness). After leaving at 85 ° C for 24 hours, the flexural strength was measured. The deflection value was evaluated as the maximum height at which the deflection occurred from the bottom.

(3) Adhesion to Polarizer: (2) A polarizer was manufactured in the same manner as in the bending measurement. The prepared polarizer was cut into a width x length (205 mm x 20 mm) to prepare a polarizer specimen. An adhesive film cut into a size of 210 mm x 25 mm x 0.5 cm (width x length x thickness) was laminated on the polarizer specimen and the adhesion between the polarizer specimen and the adhesive film was measured according to JIS 2107 standard.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

(Meth) acryl-based copolymer, an isocyanate-based crosslinking agent, and a silane coupling agent,
(A) of the hydroxyl group of the (meth) acrylic copolymer is from 2.5 mol% to 4 mol%
(B) of the alkoxysilane group of the silane coupling agent in the total sum of the number of moles of the alkoxysilane group of the silane coupling agent and the number of moles of the isocyanate group of the isocyanate crosslinking agent is from 50 mol% to 80 mol% (C) of the isocyanate group is from 20 mol% to 50 mol%
And the difference BC between B and C is 20 mol% to 56 mol%. The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, wherein the (meth) acrylic copolymer has an acid value of 0.5 mgKOH / g or less. 2. The thermoplastic resin composition according to claim 1, wherein the (meth) acrylic copolymer is a (meth) acrylic monomer having a hydroxyl group; And a monomer mixture containing at least one of (meth) acrylic monomers having an alkyl group, (meth) acrylic monomers having a heterocyclic ring, (meth) acrylic monomers having an aromatic group, and (meth) acrylic monomers having an alicyclic group, Sensitive adhesive composition. 4. The thermoplastic resin composition according to claim 3, wherein the (meth) acrylic copolymer is selected from the group consisting of 96 mol% to 97.5 mol% of unsubstituted alkyl (meth) acrylates having 1-20 carbon atoms, ) Acrylate ester in an amount of 2.5 mol% to 4.0 mol%. 4. The thermoplastic resin composition according to claim 3, wherein the (meth) acrylic copolymer comprises 76.0 mol% to 97.4 mol% of a (meth) acrylic acid ester having an unsubstituted alkyl group having 1-20 carbon atoms; 2.5 mol% to 4.0 mol% of a (meth) acrylic acid ester having an alkyl group having 2 to 20 carbon atoms and having a hydroxyl group; A pressure-sensitive adhesive composition for a polarizing plate, which is a copolymer of a monomer mixture containing at least 0.1 mol% to 20.0 mol% of at least one of (meth) acrylic monomers having a heterocycle, (meth) acrylic monomers having an alicyclic group, and (meth) acrylic monomers having an aromatic group . The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, wherein the silane coupling agent comprises a silicon compound having a mercapto group. The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, wherein the isocyanate-based crosslinking agent comprises a terminal-capped isocyanate-based crosslinking agent. The pressure-sensitive adhesive composition for a polarizing plate according to claim 1, which comprises 0.1 to 10 parts by weight of the isocyanate-based crosslinking agent and 0.1 to 10 parts by weight of the silane coupling agent based on 100 parts by weight of the (meth) acrylic copolymer. An adhesive film for a polarizing plate having an adhesive force of 1,000 gf / inch or more to a polyvinyl alcohol polarizer,
The pressure-sensitive adhesive film for a polarizing plate, wherein the pressure-sensitive adhesive film for a polarizing plate is formed of the pressure-sensitive adhesive composition for a polarizing plate according to any one of claims 1 to 8. delete A polarizer comprising a polarizer, an adhesive layer formed on one surface of the polarizer, and a protective film formed on the other surface of the polarizer, wherein the adhesive layer comprises the adhesive film for polarizer of claim 9. An optical display device comprising the polarizing plate of claim 11.

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